Facing questions about whether a high-ranking prosecutor’s actions during a murder investigation and trial constituted misconduct, the Brooklyn district attorney’s office agreed on Tuesday to allow a man imprisoned in that case to have his murder conviction vacated and his record cleared with the assurance that he will not be retried.

The agreement means that the man, Jabbar Collins, who 15 years ago was sentenced to 34 years to life in the murder of a Brooklyn landlord, will be freed later this week — the culmination of years of his own legal efforts to bring light to prosecutorial misconduct that he said deprived him of a fair trial.

The decision also spares officials from the Brooklyn district attorney’s office — most notably the hard-charging prosecutor who oversaw the case, Michael F. Vecchione — from being compelled to testify about the allegations of misconduct during a habeas corpus hearing that was set to resume this week.

The deal amounted to a rare and embarrassing admission by the Brooklyn district attorney’s office — which had initially insisted that Mr. Collins be retried — that the case had been mishandled.

Judge Dora L. Irizarry, of the United States District Court in Brooklyn, lamented that in agreeing to free Mr. Collins, the district attorney’s office had avoided a hearing that would have offered greater transparency into the case’s “troubling history.”

“It is indeed beyond disappointing, it is really sad that the district attorney’s office persists in standing firm and saying that it did nothing wrong here,” the judge said. She described the handling of the case by the district attorney’s office as “shameful.”

The case cast a new, unflattering glare on Mr. Vecchione, who has overseen numerous high-profile cases in Brooklyn and even was one of the authors of a book about his exploits in the “Mafia Cops” case. In that book, “Friends of the Family,” he described himself as “a prosecutor with a passion for justice who had spent most of his life trying to make sure bad things happened to bad people.”

But he has also been dogged by allegations of impropriety from defense lawyers, and former colleagues who say his eye for the spotlight and willingness to cut corners to win convictions have caused some cases to fall apart, including the high-profile murder trial of Roy Lindley DeVecchio, a former F.B.I. agent.

“Prosecutors are supposed to hit hard, but he went far beyond,” said Douglas E. Grover, who was Mr. DeVecchio’s lawyer.

From prison, Mr. Collins, 37, had amassed evidence of misconduct by Mr. Vecchione, whom he accused of “playing God” by threatening a witness with physical violence, failing to turn over exculpatory evidence to the defense, knowingly eliciting inaccurate testimony and making false statements.

Through a spokesman, Mr. Vecchione refused to comment on Tuesday. But in 2006, he offered a sworn affidavit denying any wrongdoing, saying that he held himself and those who worked for him “to a high professional standard.” Judge Irizarry described Mr. Vecchione’s statements in that affidavit as beyond credulity.

Brooklyn District Attorney Charles J. Hynes, who was in office during Mr. Collins’s initial trial, vigorously defended Mr. Vecchione, who he said would not face any investigation or disciplinary action.

“Anyone who knows Mike Vecchione, who has ever seen him in action, knows that he is a very, very principled lawyer,” Mr. Hynes said. He also defended the office’s handling of the case and said the decision to drop it had nothing to do with the allegations of misconduct but rather the passage of time since the slaying.

Joel B. Rudin, who represented Mr. Collins in the hearing, called Mr. Vecchione’s conduct disgraceful. “I was looking forward to confronting him with his affidavit and his statements at the trial and comparing those statements to the truth,” he said. “Obviously in the final analysis, the district attorney did not want to expose Mr. Vecchione to cross-examination.”

Photo

The chief of the rackets bureau in the Brooklyn district attorney's office, Michael F. Vecchione, in court in 2007.Credit
Pool photo by Jesse Ward

Ellen Yaroshefsky, the director of the Jacob Burns Center for Ethics in the Practice of Law at Cardozo Law School, said the decision to free Mr. Collins without a hearing raised red flags. “It is important that the D.A.’s office examine what went wrong and hold individual prosecutors accountable for any misconduct,” she said. “Transparency and accountability are essential.”

The chain of events that led to vacating the case against Mr. Collins began last month when, after years defending the handling of the case, the district attorney’s office acknowledged that a key witness had briefly recanted his testimony in the presence of a prosecutor before trial, a fact never disclosed to the defense. The office, which said it had just discovered the information, offered to release Mr. Collins if he pleaded guilty to a reduced charge of manslaughter, but Mr. Collins declined, saying he was willing to risk retrial to clear his name.

On Tuesday, in a court packed with family members including his three children, Mr. Collins thanked Judge Irizarry “for finally giving me the day in court that I have been deprived of the last 15 years of my life.”

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Several family members of Abraham Pollack, the Brooklyn landlord and father of nine who was shot and killed in 1994, were also in the courtroom; they said they remained convinced that Mr. Collins was guilty.

While the decision concludes Mr. Collins’s long battle for freedom, it remains unclear whether the allegations of misconduct will have any impact on Mr. Vecchione, the chief of the rackets bureau and a 25-year veteran of the district attorney’s office.

“Unquestionably, whether you agree with him or not, whether you like him or not, he’s an aggressive prosecutor,” said Richard E. Mischel, a defense lawyer who faced Mr. Vecchione in the case of the Brooklyn political leader Clarence Norman Jr. “That’s not a criticism, it’s just an observation.”

Bruce Barket, a defense lawyer who pushed successfully to have another man who had been convicted of murder released during a 2003 habeas corpus hearing that featured similar allegations of misconduct, said he believed that Mr. Vecchione had a history of crossing the line in pursuit of convictions.

Mr. Barket said that in his case, he presented evidence that Mr. Vecchione had concealed from the defense the information that a key witness had been arrested on rape charges. Then at the trial, Mr. Vecchione allowed the witness to lie on the stand when he stated that he had never sought or received anything in return for his testimony — when, in fact, the lawyer for the witness said that he had sought a deal.

Immediately after the trial, the witness was allowed to plead guilty to reduced charges that did not include rape.

The cooperation agreement was personally signed by Mr. Vecchione. The agreement was never revealed to the defense in two subsequent trials that he supervised. And Mr. Vecchione also later, in a letter to the Nassau County district attorney’s office, denied the existence of the agreement.

The district attorney’s office also agreed to settle that case shortly before a ruling in the habeas corpus hearing from Judge Edward R. Korman of United States District Court in Brooklyn, who had expressed skepticism about Mr. Vecchione’s testimony. The defendant was immediately released.

“Everyone pushes the envelope to some degree; everyone looks for strategic advantage,” Mr. Barket said. “That’s fine. But you have to play by the rules. What I’ve not seen is someone who disregards the rules so flagrantly. He looks at the rules as obstacles.”

“I don’t understand how he can continue to prosecute criminal cases,” he added.

In the murder case vacated on Tuesday, there were serious questions raised about each of the three main witnesses who testified against Mr. Collins at the original trial. One of them, Angel Santos, was the only person to testify in the aborted habeas corpus hearing, before the district attorney agreed to the unconditional release of Mr. Collins.

Speaking reluctantly and at times saying he was unable to answer questions because his memory of the period “was all screwed up” by drugs, Mr. Santos described being coerced by Mr. Vecchione at the initial trial. “I told them I didn’t want to get involved, so what they did, they locked me up,” he testified. Mr. Vecchione repeatedly threatened to hit him and said, “If you don’t testify you’re going to be in jail a long time,” Mr. Santos said. He said he was held in jail for a week before he agreed to testify and was kept in custody until he testified against Mr. Collins.

In 2006, Mr. Vecchione signed a sworn affidavit stating: “No deals were made with witnesses that were not disclosed by me to the court and the defense. No witness ever recanted a prior statement or grand jury testimony. No witness had to be threatened or forced to testify.”

Mr. Rudin, the defense lawyer, declined to say whether Mr. Collins would file a civil suit or any formal complaints relating to the case. “Everything will be studied at the appropriate time. Right now we have to get him home and get him with his family,” he said. “But it’s not going to end here.”

A version of this article appears in print on June 9, 2010, on Page A18 of the New York edition with the headline: Facing Misconduct Claims, Brooklyn Prosecutor Agrees to Free Man Held 15 Years. Order Reprints|Today's Paper|Subscribe